Y.1731 delay measurement (Bridge): Up and Down MEPs

This feature adds support for ITU-T Y.1731 Ethernet delay measurement on bridge services using both Up and Down maintenance association end points (MEPs). Y.1731 delay measurement enables you to measure two-way frame delay and frame delay variation between MEPs for network performance monitoring and SLA verification. Up MEPs direct OAM traffic toward the bridge service and can include delay introduced within the bridge, while Down MEPs direct OAM traffic toward the interface on which the MEP is configured.